For about 40 years, nuclear physicists at the University of Minnesota smashed atoms in hopes of discovering what lies beyond. In 1938, a machine called the ‘Van de Graaff’ was built behind Tate Laboratory of Physics, but was torn down in this year’s renovations of the lab.
The aim of the project, led by physics professors John H. Williams and John T. Tate, was to make breakthroughs in understanding atomic structure.
The basic building block of all matter — the atom — is composed of negatively charged electrons and a positive nucleus, which contains protons and neutrons. The Van de Graaff machine was built to better understand the atom’s nucleus. In the 1920s, nuclear physics was a relatively new field, and to break apart an atom required a high-powered machine, said Benjamin Bayman, a former professor and current theoretical nuclear physics researcher at the University of Minnesota.
This spurred the creation of the Van de Graaff, said biophysics professor, John Broadhurst.
The machine shot atomic particles at each other in hopes of either exciting the nucleus or breaking it apart, Bayman said.
“[It’s like] covering a piano in a dark room and throwing bricks at it to understand how it’s made, based on the sound,” he said.
The Van de Graaff machine was one of the most powerful machines at that time, Bayman said, and gave the University a leg-up in nuclear physics — placing the school above most other institutions in the country.
Broadhurst said the machine led to correspondence between Williams and physicist J. Robert Oppenheimer who told Williams to try new experiments with the Van de Graaff. Oppenheimer was the head of the Los Alamos Laboratory, the lab responsible for creating the atomic bomb.
Though the Van de Graaff was an advanced machine at that time, nuclear structure proved hard to smash, though scientists still gathered data, Broadhurst said.
After World War II, interest in nuclear physics spiked due to the atomic bombs used to end the war, Bayman said.
By this time John H. Williams led the physics department at the University, and was able to get two new accelerators that were built along the Mississippi River — the Linac in the 1950s, and the Tandem Van de Graaff accelerator in 1966.
The Linac was the most powerful accelerator at the time, Broadhurst said.
Williams passed away before the Tandem was complete, and Broadhurst was made the Director of Operations of both machines.
The Tandem and Linac accelerators made the original Van de Graaff machine obsolete, and it was abandoned, Bayman said.
“[But] nuclei are complicated structures … and by the 1970s most possible experiments that can be done were done,” he said.
After the nuclear disasters at Chernobyl in Russia, and Three Mile Island in Pennsylvania, public interest in nuclear physics dwindled, he said. This, in tandem with increasing maintenance costs and declining public interest, led to the defunding of institutional atom smashers, with efforts refocused in national laboratories, Bayman said.
The Tandem and Linac accelerators at the University were completely defunded by the 1990s. Both were torn down after Interstate 35W collapsed.
Today, nuclear physicists and students must travel to larger, more powerful machines at Fermilab and CERN in Switzerland to do this type of experimentation, he said.
Jenny Allan, communications director for Tate Lab, said the largest physics project the University is involved with is Fermilab’s NOvA Neutrino Project.
The University is also part of preliminary planning of a larger physics project called the Deep Underground Neutrino Experiment, Allan said.
Broadhurst said after nearly a century of experiments, physicists are still not entirely certain how nuclei are structured, but scientists have gathered a huge amount of data from their experiments. To make matters more complicated, scientists have discovered smaller particles within the neutron and proton of an atom’s nucleus.
“Someday there will be a breakthrough,” Broadhurst said.